This patch creates a sample manager next to the sound manager. The

This patch creates a sample manager next to the sound manager. The
difference between the two is this: A sample is file related and sound
is a authonomus entity. This means you can have several sounds pointing
to a single sample. In that case, just one sample is loaded into memory.
The advantage is you can play the same sample with different pitch or
volume, but with just one  sample loaded into memory.

To fully support this there is a new fucntion call:

    FGSimpleSound *sample = new FGSimpleSound("filename");
    mgr->add(sample, "name");

should be replaced by:

    FGSimpleSound *sample = mgr->add("name", "filename");

But the old behaviour is still supported with one minor change, sounds
with the same name aren't supported anymore.

Erik